The basic goal of this project is an analysis of the neural systems and mechanisms underlying auditory learning and discrimination. Patterns of activity of single neurons in auditory and association areas of the cerebral cortex to auditory stimuli of varying complexity will be studied in the anesthetized and unanesthetized preparations. In the latter, tone frequency and pattern discrimination paradigms will also be used, with concomitant recording of single neuron activity. An experimental preparation and procedures have been developed using evoked neuronal activity in the pyramidal tract in the unanesthetized, immobilized cat as a "behavioral response which can be conditioned and trained. This preparation makes possible analysis of alterations in neuronal activity in both auditory and non-auditory brain structures during the course of single session acquistion of response to tone, from frequency discrimination and generalization, and tone pattern discrimination.